1. Field of the Invention
The present invention relates to jet engines, specifically to turbofan jet engine assemblies.
2. Description of the Related Art
A turbofan is a type of aircraft jet engine based around a gas turbine engine. Turbofans provide thrust using a combination of a ducted fan and a jet exhaust nozzle. Part of the airstream from the ducted fan passes through the core, providing oxygen to burn fuel to create power. However, the rest of the air flow bypasses the engine core and mixes with the faster stream from the core, significantly reducing exhaust noise. The rather slower bypass airflow produces thrust more efficiently than the high-speed air from the core, and this reduces the specific fuel consumption.
A few designs work slightly differently and have the fan blades as a radial extension of an aft-mounted low-pressure turbine unit. Turbofans have a net exhaust speed that is much lower than a turbojet. This makes them much more efficient at subsonic speeds than turbojets, and somewhat more efficient at supersonic speeds up to roughly Mach 1.6, but have also been found to be efficient when used with continuous afterburner at Mach 3 and above. However, the lower speed also reduces thrust at high speeds.
Some improvements have been made in the field. Examples of references related to the present invention are described below in their own words, and the supporting teachings of each reference are incorporated by reference herein:
U.S. Pat. No. 7,568,347, issued to Leland et al., discloses a diverterless hypersonic inlet (DHI) for a high speed, air-breathing propulsion system reduces the ingested boundary layer flow, drag, and weight, and maintains a high capture area for hypersonic applications. The design enables high vehicle fineness ratios, low-observable features, and enhances ramjet operability limits. The DHI is optimized for a particular design flight Mach number. A forebody segment generates and focuses a system of multiple upstream shock waves at desired strengths and angles to facilitate required inlet and engine airflow conditions. The forebody contour diverts boundary layer flow to the inlet sides, effectively reducing the thickness of the boundary layer that is ingested by the inlet, while maintaining the capture area required by the hypersonic propulsion system. The cowl assembly is shaped to integrate with the forebody shock system and the thinned boundary layer region.
U.S. Pat. No. 7,207,520, issued to Lundy et al., discloses an advanced aperture inlet (AAI) uses a three-dimensional, mixed compression inlet design derived from computational fluid dynamics (CFD) by streamline tracing a supersonic section from an axisymmetric mixed compression inlet solution. The axisymmetric design is used to obtain a CFD solution with slip wall boundaries at the inlet design point and serves as a flow field generator for the AAI. The AAI geometry is obtained by projecting a desired aperture shape onto a surface model of the external oblique shock. Streamline seeds are located on the projected aperture segments and transferred into the CFD solution space. The streamlines generated by these seeds inside the CFD solution space are then used as a wireframe to define the supersonic diffuser back to the throat location. Traditional design techniques are then used to define the subsonic diffuser from the inlet throat to the engine face.
U.S. Pat. No. 6,966,524, issued to Stuhr, discloses an engine nacelle for use with aircraft. In one embodiment, an engine nacelle includes an inlet having an inlet aperture and an outlet having an outlet aperture. In one aspect of this embodiment, the engine nacelle further includes a first side portion, a second side portion, and a third side portion. The first side portion can extend at least generally between a first edge portion of the inlet aperture and a third edge portion of the outlet aperture. The second side portion can be offset from the first side portion and extend at least generally between a second edge portion of the inlet aperture and a fourth edge portion of the outlet aperture to define a first interior portion. The third side portion can be offset from the second side portion and extend at least generally from the second edge portion of the inlet aperture toward the fourth edge portion of the outlet aperture to define a second interior portion. In another aspect of this embodiment, the first interior portion is configured to house an engine, and the second interior portion is configured to house a landing gear assembly.
U.S. Pat. No. 6,793,175, issued to Sanders et al., discloses a supersonic external-compression inlet comprises a generally scoop-shaped supersonic compression section for diffusing a supersonic free stream flow. The supersonic compression section includes a main wall having a leading edge and a throat portion downstream of the leading edge, and side portions joined to opposite side edges of the main wall so as to form a generally scoop-shaped structure. The side portions advantageously extend into the supersonic flow stream far enough to encompass the initial oblique shock wave that is attached to the leading edge of the main wall. The main wall has an inner surface formed generally as an angular sector of a surface of revolution, the inner surface of the main wall coacting with inner surfaces of the side portions to define a three-dimensional external-compression surface. The supersonic external-compression inlet also includes a subsonic diffuser section arranged to receive flow from the supersonic compression section and to diffuse the flow to a subsonic condition. A variable-geometry inlet includes an external ramp hinged about its forward edge and forming a portion of the inner surface of the scoop-shaped diffuser, pivotal movement of the external ramp serving to vary a throat size of the inlet. The subsonic diffuser includes an internal ramp hinged about its aft edge for maintaining a smooth transition from the external ramp.
U.S. Pat. No. 4,073,440, issued to Hapke, discloses a combination primary and fan air thrust reversal control systems for long duct fan jet engines are disclosed. In one form, the system spoils and expands primary air and, then, allows the spoiled, expanded air to exit from the fan air duct exhaust nozzle while directing fan air in a thrust reversal direction out cascade vanes circumferentially located in the aft portion of the engine nacelle. In other forms, the system directs unequal pressure fan air and primary air through separate thrust reversal ducting and out cascade vanes circumferentially located in the engine nacelle. In equal pressure fan air and primary air systems, the air may be mixed in ducting prior to being emitted from common cascade vanes, or may be maintained separate prior to emission. In still other forms, the primary air is pre-exhausted through separate nozzles located in the primary duct wall, and a portion is then exhausted through the nacelle cascade vanes. In all systems, circumferential cascade vanes are radially located in the rear portion of the engine nacelle and are exposed by rearwardly translating the aft portion of the nacelle, which forms the fan air duct exhaust nozzle. As the fan air duct exhaust nozzle is translated rearwardly, fan air duct blocker doors and, depending on the system, primary air duct blocker doors are positioned to divert the jets for thrust reversing. As an alternative to a primary air duct blocker door, the primary air duct exhaust nozzle is translated rearwardly to contact the exhaust cone or plug and, thereby, valve off the primary air duct. In this case, the fan and primary exhaust nozzles are translated rearwardly as unit.
The inventions heretofore known suffer from a number of disadvantages which include being inefficient, being limited in conversion, being ineffective, being limited in speed, being limited in performance, and being limited in adaptation.
What is needed is a turbofan jet engine that solves one or more of the problems described herein and/or one or more problems that may come to the attention of one skilled in the art upon becoming familiar with this specification.